A human monoclonal antibody blocking SARS-CoV-2 infection

Abstract

The emergence of the novel human coronavirus SARS-CoV-2 in Wuhan, China has caused a worldwide epidemic of respiratory disease (COVID-19). Vaccines and targeted therapeutics for treatment of this disease are currently lacking. Here we report a human monoclonal antibody that neutralizes SARS-CoV-2 (and SARS-CoV) in cell culture. This cross-neutralizing antibody targets a communal epitope on these viruses and may offer potential for prevention and treatment of COVID-19.

Fig. 1. 47D11 neutralizes SARS-CoV and SARS-CoV-2.

a Binding of 47D11 to HEK-293T cells expressing GFP-tagged spike proteins of SARS-CoV and SARS-CoV-2 detected by immunofluorescence assay. The human mAb 7.7G6 targeting the MERS-CoV S1_B spike domain was taken along as a negative control, cell nuclei in the overlay images are visualized with DAPI. b Antibody-mediated neutralization of infection of luciferase-encoding VSV particles pseudotyped with spike proteins of SARS-CoV and SARS-CoV-2. Pseudotyped VSV particles pre-incubated with antibodies at indicated concentrations (see Methods) were used to infect VeroE6 cells and luciferase activities in cell lysates were determined at 24 h post transduction to calculate infection (%) relative to non-antibody-treated controls. The average ± SD from at least three independent experiments with technical triplicates is shown. Iso-CTRL: an anti-Strep-tag human monoclonal antibody was used as an antibody isotype control. c Antibody-mediated neutralization of SARS-CoV and SARS-CoV-2 infection on VeroE6 cells. The experiment was performed with triplicate samples, the average ± SD is shown. Source data are provided as a Source Data file.

Fig. 2. The neutralizing 47D11 mAb binds SARS1-S and SARS2-S RBD without eliminating receptor interaction.

a ELISA-binding curves of 47D11 to S_ecto (upper panel) or S1_A and S1_B (RBD: receptor-binding domain) (lower panel) of SARS-S and SARS2-S coated at equimolar concentrations. The average ± SD from two independent experiments with technical duplicates is shown. b Interference of antibodies with binding of the S-S1_B of SARS-CoV and SARS-CoV-2 to cell surface ACE2-GFP analyzed by flow cytometry. Prior to cell binding, S1_B was mixed with mAb (mAbs 47D11, 35F4, 43C6, 7.7G6, in H2L2 format) with indicated specificity in a mAb:S1_B molar ratio of 8:1 (see Supplementary Fig. 3 for an extensive analysis using different mAb:S1_B molar ratio’s). Cells are analyzed for (ACE2-)GFP expression (x axis) and S1_B binding (y axis). Percentages of cells that scored negative, single positive, or double positive are shown in each quadrant. Experiment was done twice, a representative experiment is shown. c Divergence in surface residues in S1_B of SARS-CoV and SARS-CoV-2. Upper panel: Structure of the SARS-CoV spike protein S1_B RBD in complex with human ACE2 receptor (PDB: 2AJF). ACE2 (wheat color) is visualized in ribbon presentation. The S1_B core domain (blue) and subdomain (orange) are displayed in surface presentation using PyMOL, and are visualized with the same colors in the linear diagram of the spike protein above, with positions of the S1 and S2 subunits, the S ectodomain (S_ecto), the S1 domains S1_A-D and the transmembrane domain (TM) indicated. Lower panel: similar as panel above with surface residues on S1_B of SARS-CoV that are at variance with SARS-CoV-2 colorored in white. Source data are provided as a Source Data file.